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Proceedings Paper

Insights gained from regression analysis of PpIX fluorescence imaging undertaken during routine dermatological photodynamic therapy
Author(s): Jess Tyrrell; Cheryl Paterson; Alison Curnow
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Paper Abstract

Clinical protoporphyrin IX (PpIX) fluorescence imaging was conducted using a pre-validated, non-invasive imaging system (Dyaderm, Biocam, Germany) during routine methyl aminolevulinate (MAL)-PDT treatment of 172 patients with licensed dermatological indications (37.2% actinic keratosis, 27.3% superficial basal cell carcinoma and 35.5% Bowen’s disease). Linear and logistic regressions were employed to model any relationships between variables that may have affected PpIX accumulation and/or PpIX photobleaching during irradiation and thus clinical outcome at three months. Patient age was found to be associated with lower PpIX accumulation and photobleaching, however only a reduction in PpIX photobleaching appeared to consistently adversely affect treatment efficacy. Clinical clearance was reduced in lesions located on the limbs, hands and feet with lower PpIX accumulation and subsequent photobleaching adversely affecting the outcome achieved (OR: 0.5 (0.2, 0.9; p<0.05). If air cooling pain relief was employed during light irradiation, PpIX photobleaching was significantly reduced (p < 0.05) and this resulted in an approximate three-fold reduction in the likelihood of achieving clinical clearance (OR: 0.4 (0.2, 0.7; p<0.01). PpIX accumulation and photobleaching are therefore concluded to be important indicators of dermatological MAL-PDT treatment success and anything that adversely effects them has the potential to reduce treatment efficacy. PpIX photobleaching during the first treatment was found to be an excellent predictor of clinical outcome across all lesion types and non-invasive imaging of PpIX fluorescence during MAL-PDT continues to provide important treatment insights that can be utilised to improve treatment protocols and thus clinical outcomes.

Paper Details

Date Published: 7 August 2019
PDF: 5 pages
Proc. SPIE 11070, 17th International Photodynamic Association World Congress, 110702Y (7 August 2019); doi: 10.1117/12.2525727
Show Author Affiliations
Jess Tyrrell, Univ. of Exeter Medical School (United Kingdom)
Cheryl Paterson, Univ. of Exeter Medical School (United Kingdom)
Alison Curnow, Univ. of Exeter Medical School (United Kingdom)

Published in SPIE Proceedings Vol. 11070:
17th International Photodynamic Association World Congress
Tayyaba Hasan, Editor(s)

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